There is no admission that the background art disclosed in this section legally constitutes prior art.
Assay tests have been employed to analyze test samples such as urine samples to determine whether or not they contain substances such as HCG indicating pregnancy, drugs of abuse, or other.
For example, reference may be made to the following United States patents, each of which is incorporated herein by reference:
PATENT NO.INVENTORISSUE DATE4,033,723Givner, et al.Jul. 05, 19774,123,509Banik, et al.Oct. 31, 19784,348,207CappelSep. 07, 19824,450,239ChattertonMay 22, 19844,700,711CarlsonOct. 20, 19875,182,216Clayton, et al.Jan. 29, 19935,580,794Allen, et al.Dec. 3, 19965,656,503May, et al.Aug. 12, 19975,786,220Pronovost, et al.Jul. 28, 19985,837,546Allen, et al.Nov. 17, 19986,063,026Schauss, et al.May 16, 20006,150,178Cesarczyk, et al.Nov. 21, 20006,235,241B1Catt, et al.May 22, 2001
Test strips, as disclosed in one or more of the foregoing patents, are employed to receive a test sample such as a urine sample for performing an assay test. For example, a pregnancy test strip has been used to collect a urine sample to react with a reagent to produce a visible line such as a line having a pink/purple color. It is sometimes difficult to make a subjective determination as to the intensity of the color of the line relative to a comparison line. Thus, false positive indications are sometimes possible.
In an attempt to help interpret the results of such assay test, the U.S. Pat. No. 6,235,241B1 discloses a test strip disposed within a casing or housing, and includes a light source with diffusers to illuminate the test strip to help the user to interpret the results of a test. Light sensors on the other side of the test strip detect the light shining through the test strip. However, such a device is complex in its construction, and thus relatively expensive to manufacture.
For the purpose of making a relatively inexpensive assay test device, which can be for single use only, as disclosed in U.S. Pat. Nos. 5,580,794 and 5,873,546, a disposable device includes a test membrane containing a reagent for receiving a liquid test sample. A set of electrodes detects the presence of movement of the sample liquid to activate the device electrically to cause sensors to sense the results of the chemical reaction of the reagent with the test sample. In this regard, as the liquid sample moves toward the electrodes, the reaction is occurring and the results are sensed once the liquid reaches the electrodes. Alternatively, the device may be activated electrically by closing a switch when it is removed from its pouch, and the reaction results are sensed after a specified time.
However, when the electrodes are used, the reaction time may be dependent on the length of time it takes for the movement of the liquid sample along the membrane. Thus, the reaction time may not be precisely controlled and repeatable, and thus accuracy may be adversely affected. When the alternative approach of sensing the reaction results after initially turning on the device, following a time delay, the reaction time is even less precisely controlled, because there is little or no control over when the sample is introduced to the membrane following the activation of the device.
Therefore, it would he highly desirable to have a new and improved testing device and method of using it, which are relatively more accurate in the determination of the test results, while at the same time being relatively inexpensive to manufacture and to use. Thus, such a device and method may, if desired, be employed for a single use, and yet be relatively accurate in its use.